OiOverview of Stormwa ter Effects on Water Quality

wq-strm7-81 Stormwater Module 1 Minnesota Pollution Control Agency Training goals

† Recognize the wide † Identify how land variety of use, management pollutants in urban practices, and stormwater runoff natural factors that can impair affect pollutant receiigiving waters ldigloading

Stormwater module 1: Overview of stormwater effects on water quality 2 What is urban stormwater?

Water running off an urban land surface after a rainfall or snowmelt event

Stormwater module 1: Overview of stormwater effects on water quality 3 Urban areas have less infiltration and evaporation and more runoff than forested or grassland areas

Two most important factors: 1. amount of impervious surface 2. connectedness of impervious surface

Source for figure: http://duluthstreams.org/understanding/stormwater_hydrology.html Stormwater module 1: Overview of stormwater effects on water quality 4 How do we affect the quality of stormwater?

Chemicals that we apply to the ldlandscape are carr idied with runoff water to receiving waters

Stormwater module 1: Overview of stormwater effects on water quality 5 What environmental effects are associated with stormwater runoff?

† Stormwater usually discharges to a lake, river/stream or wetland † Increased runoff may cause flooding † Chem ica ls may be tox ic to organisms † Characteristics (habitat) of the receiving water body mayyg change

Stormwater module 1: Overview of stormwater effects on water quality 6 What water body impairments are associated with stormwater?

nutrients (primarily phosphorus) and pathogens Lakes impair the lake for recreational use

Rivers/ nutrients, sediment, chloride, pathogens, and temperature impair the river/stream for streams aquatic vegetation, recreation, and habitat

nutitrien ts an d se dimen tit impa ir we tlan ds for Wetlands habitat

Stormwater module 1: Overview of stormwater effects on water quality 7 Phosphorus

Concentrations † are greatest from lawns and residential areas with considerable tree canopy † from all areas exceed wat er qua lity stdd*tandard* 2.5

Lawns

) 2.0 LL Streets 1.5 Parking lots ation (mg/ r r 1.0 Roofs

Water quality

Concent 0.5 standard*

0.0 * Standard varies with area of state and characteristics of lake Stormwater module 1: Overview of stormwater effects on water quality 8 Factors increasinggp phos phorus loadin g

Increased † impervious area † connectivity of imperv iou s area † turfgrass and leaf contributions † concentrations of soluble phosphorus † soil erosion Natural factors (rainfall, soil)

Stormwater module 1: Overview of stormwater effects on water quality 9 Sediment

† Most pollutants are associated with finer sediment Annual Sediment Load (lbs/acre) † Construction is Freeways a major source Commercial Industrial † Varies with Shopping Center precipitation Multi-family characteristics Small residential lot Large residential lot † Affects biota Parks 0 200 400 600 800 1000 1

Stormwater module 1: Overview of stormwater effects on water quality 10 Pathogens

† Multiple urban sources, including illicit 100000000 1000000

discharges, residential, mL 100 Standard // 10000 internal loading 100 1 Colonies t et y let e top re ee ut t ewa wag Forest oof c s e R riv al lawns s ffi ti ffic str w ra n a Basin o a † t tial d tr R Importance of different l parking lotsh ide g n cia Hi ide Res Low es R sources varies with Commer precipitation † Affects recreational use

Stormwater module 1: Overview of stormwater effects on water quality 11 Chlorides

† Major source is road salt † Highest concentrations in winter † Affects biota

Data for Shingle Creek

Stormwater module 1: Overview of stormwater effects on water quality 12 Temperature

Varies † with type of surface ((ge.g. asphalt, concrete, grass) † during a rain event Effects biota Data for Miller Creek

Stormwater module 1: Overview of stormwater effects on water quality 13 Flow

† NotanimpairmentbyNot an impairment by itself, but a surrogate for other pollutants † A function of impervious surface and connectivity of drainage system † Affects loading of most pollutants; b iota

Stormwater module 1: Overview of stormwater effects on water quality 14 Metals,,g organics , nitro gen

† Waters are currently not assessed for these † Concentrations are elevated in urban runoff † Characteristics and effects vary with each pollutant

Stormwater module 1: Overview of stormwater effects on water quality 15 Summary

† Urban areas have more runoff and less infiltration and evaporation than forested or grassland areas † Urban runoff contains many pollutants that can affect a receiving water body † Natural and manman--inducedinduced factors affect the amount of pollutant loading that results from urban stormwater runoff

Stormwater module 1: Overview of stormwater effects on water quality 16